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Journal of the American College of Nutrition, Vol. 23, No. 6, 748S-750S (2004)
Published by the American College of Nutrition

Developed Determination Method of Ultra Trace Elements and Ultra Trace Element Levels in Plasma of Rat Fed Low Magnesium Diet

Mieko Kimura, PhD, Kazuto Honda, Atsuko Takeda, MD, Masayo Imanishi and Takahisa Takeda, MD

Takeda Research Institute of Life Science, Kyoto (M.K., A.T., M.I., T.T.)
Perkin-Elmer Japan Co. Ltd., Osaka (K.H.), JAPAN

Address reprint requests to: Mieko Kimura, PhD, Takeda Research Institute of Life Science, Kyoto 600-8813, JAPAN. E-mail: mkimura{at}mbox.kyoto-inet.or.jp


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
Background: Homeostatic mechanisms keep plasma mineral concentrations largely unchangeable, and are not always reflective of the nutritional status. For that reason, nutritional assessment is difficult and another biological index may be of value. Recently, improvement of measuring instruments has permitted more accurate measurement of trace and ultra trace elements.

Methods: A new determination method for trace and ultra trace elements in rat plasma, that uses an inductively coupled plasma mass spectrometry (ICP-MS Elan-6000, Perkin Elmer, Co., USA) without pre-treatment has enabled study of basic data of ultra trace element concentrations for the first time.

Results: The effect of low magnesium (Mg) intake, as compared with the effect of a normal diet, status of 10 trace and ultra trace element status was studied in 12 young male Wistar rats (3-weeks-old), divided into two groups and fed a normal diet or low Mg diet for 4 weeks. The plasma was diluted with ultra pure water (TAMAPURE-AA: Tama Chemical Co., Japan). Ten trace and ultra trace element (As: 75, Se: 82, Rb: 85, Sr: 87, Mo: 95, Ba: 137, Ta: 181, Ir: 193, Au: 197, Pb: 208) concentrations in the plasma were measured with ICP-MS Elan 6000. As, Rb, Sr, Ta, Ir and Au concentrations were significantly high in the plasma of low Mg rats, compared to levels in rats fed normal diets. Essentiality for mammals has been certified for Se, Rb, Mo, As and Pb, but not yet for Sr, Ba, Au, Ir and Ta.

Conclusions: These results prove that trace and ultra trace element concentrations in plasma are changeable by nutritional conditions, and suggest that new physiological functions may be found for these elements, and that they may be proved to be essential for mammals.

Key words: ultra trace elements, low magnesium diet, rat, plasma


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
Homeostatic mechanisms maintain fixed, seemingly unchangeable mineral concentrations in blood plasma or blood, and the measured values do not necessarily reflect the nutritional status [1–3]. For that reason, nutritional assessment is difficult and another biological determination may be of value [4]. Recent development of new improved measuring instruments has provided the means to determine trace and ultra trace elements more accurately. In this report, a newly developed determination method for trace and ultra trace elements in the rat plasma was used. This is an inductively coupled plasma mass spectrometry, that has permitted study of basic data of trace element concentration, for the first time. At the same time, the influences of low magnesium (Mg) intake to the 10 trace and ultra element status in rats were investigated.


   METHODS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
RESULTS AND DISCUSSION
 REFERENCES
 
The experimental conditions are shown in Table 1. The plasma was diluted by ultra pure water (TAMAPURE-AA: Tama Chemical Co., Japan). Plasma concentrations of three trace elements (Sr: 87, Rb: 85, Pb: 208) and seven ultra trace element (As: 75, Se: 82, Mo: 95, Ba: 137, Ta: 181, Ir: 193, Au: 197,) were measured with inductively coupled plasma mass spectrometry (ICP-MS Elan 6000, Perkin Elmer, Co., USA) by standard addition method.


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  		Table 1. ICP-MS Operating Conditions

 
Twelve young male Wistar rats (3-weeks-old) were divided into two groups and fed a normal diet (control) or low Mg diet (1/10Mg) for 4 weeks. Table 2 shows the composition of diets. Diet and distilled water were provided ad lib, and after 4 weeks, blood was collected from the abdominal aorta under sodium pentobarbital anaesthesia. Plasma was separated from blood cells by centrifugation.


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  		Table 2. Composition of Diets (%)

 

   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS AND DISCUSSION
REFERENCES
 
The trace elements: Sr, Rb, Pb and the ultra trace elements: As, Se, Mo, Ba, Ta, Ir, Au were detected in rat plasma. The results of elemental analysis are shown in Table 3. As, Rb, Sr, Ta, Ir and Au concentrations were significantly (p < 0.05) higher in the plasma of low Mg rats, compared to those in control rats. The relationship between trace element concentrations in rat plasma fed low Mg diet and rats fed control diet are shown in Tables 4 and 5. There was significant correlation between As and Mo (p = 0.026), Rb and Au (p = 0.034), Sr and Mo (p = 0.013), Ta and Ir (p = 0.009) in the rat plasma of the control group. There was a significant correlation between As and Sr (p = 0.043), As and Mo (p = 0.026), Se and Ir (p = 0.023) in the plasma of rats fed a low Mg diet. Some investigators observed the interactions between essential trace and ultra trace elements [5–8]. Essentiality for mammals was certified for Se, Rb, Mo, As and Pb, and not yet for Sr, Ba, Au, Ir and Ta [9–11].


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  		Table 3. Trace Element Concentrations in Rat Plasma (µg/L)

 

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  		Table 4. Correlation Coefficient among Trace Elements (Control)

 

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  		Table 5. Correlation Coefficient among Trace Elements (1/10Mg)

 
These results prove that ultra trace element concentrations in plasma are changeable by nutritional conditions, and suggest possibilities for finding that they possess physiological functions and possibly proving that these elements are essential.

Received August 5, 2004.
   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 

  1. Kimura M, Harada T, Itokawa Y: Changes in blood pressure, body temperature, serotonin and tissue mineral levels in magnesium deficient rats. JJsMgR2 :7 –14,1983 .
  2. Iwabuchi A, Notani C, Tsutsui Y, Kimura M, Itokawa Y: Change in tissue mineral levels in deficient rats. JJMgR4 :45 –51,1985 .
  3. Matsuda A, Kimura M, Yokoi K, Kabata H, Itokawa Y: Changes in Trace element concentrations intravenous injection of an essential trace-element preparation for parental use in rats. Jpr J Hyg44 :887 –892,1989 .
  4. Matsuda A, Kimura M, Kataoka M, Ohkuma S, Sato M, Itokawa Y: Quantifying manganese in lymphocytes to assess manganese nutritional status. Clin Chem35 :1939 –1941,1989 .[Abstract/Free Full Text]
  5. Nielsen FH, Hunt CD, Uthus EO: Interactions between essential trace and ultra trace elements. NY Acad Sci355 :152 –164,1980 .
  6. Kimura M, Yokoi K: Iron accumulation in tissues of magnesium-deficient rats with dietary iron overload. Biol Trace Elem Res51 :177 –197,1996 .[Medline]
  7. Kimura M, Ujihara M, Yokoi K: Tissue manganese levels and liver pyruvate carboxylase activity in magnesium-deficient rats. Biol Trace Elem Res52 :171 –179,1996 .[Medline]
  8. Nielsen FH: Present knowledge in nutrition8 :397 –411,2002 . Ed. By Bowman BA & Russell RM.
  9. Mertz W: The essential trace elements. Science213 :1332 –1338,1981 .[Abstract/Free Full Text]
  10. Nielsen FH: New essential trace elements for the life sciences. Biol Trace Elem Res27 ,599 –611,1990 .




This Article
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Right arrow Articles by Kimura, M.
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Right arrow Articles by Kimura, M.
Right arrow Articles by Takeda, T.

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